It's a street/strip car - unless (and even with) GV a PG is very limited in SLR vs. RPM in OD.
Ideally, you want a trans that keeps your existing axle ratio (save $$) and has deep enough OD to slow the engine down, and still enough 1st X axle for a decent launch and traffic. The ratio "spread" (first to last) should be at least 3:1, I have 4:1, 6 speeds are even larger.
My factory (non-MoPar) is:
1 2.804:1
2 1.531:1
3 1.00:1
OD .705:1
axle 3.77:1
SLR (overall torque multiplication) 10.6:1 + stall ratio, equal to 727 with 4.33 axle.
With 26.6" tire, 90 mph is 3,000 RPM

Not sure how much advantage in 6L80 vs 4L80, but certainly more complex, heavier, possibly more floor, X-member work.